Investigation deals with blood coagulation and hemophilia with a study of the hemophilias in dogs and von Willebrand disease in dogs and swine from genetic, biochemical and pathologic points of view. Specific areas of investigation include studies of: a) genetics and pathophysiology of canine hemophilia A; b) study of canine and porcine von Willebrand disease and the platelet aggregating von Willebrand factor; c) purification and study of venom coagglutinin (VCA), an "activator" of the von Willebrand factor; and the development and application of a new test for von Willebrand factor, the VCA test, with lyophilized platelets; and d) the study of acute and chronic vascular pathology in relation to plasma and endothelial cell von Willebrand factor.